In a computer system, connection is made between each device through a signal transmission pathway, such as a bus, and each of the devices exchanges signals through the signal transmission pathway. For example, a Central Processing Unit (CPU) is connected to peripheral equipment by a bus, and exchanges signals with the peripheral equipment through the bus. Known methods to increase the communication speed between devices include raising the clock rate of a clock signal, and increasing the number of signal lines.
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Japanese Laid-Open Patent Publication No. 2009-171081
However, raising the clock rate affects the characteristic impedance of the signal transmission pathway, and affects external noise (for example signal waveform deterioration due to the skin effect and extraneous electromagnetic radiation), with waveform breakdown, such as overshoot or undershoot, sometimes generated in the transmitted signal. There is accordingly a need to shape the waveform of the signal by providing an emphasis circuit and a de-emphasis circuit on the signal transmission side, and providing an equalizer circuit on the signal receiving side. Increasing the number of signal lines leads to an increase in consumed current, manufacturing cost, placement surface area, and the like, and leads to interference between the signal lines.
An object of an aspect of technology disclosed herein is to increase the signal transmission volume per unit time.